DIY: 12" Home Subwoofer Part 3

Hi again. Last time we made a cozy for the box out of some industrial felt. That made it fit into our living room without looking like a typical, "black speaker". This week we will complete the subwoofer and fire it up. Follow along for the exciting conclusion of "The Case of the DIY Subwoofer…"

We needed a little extra bracing in the cabinet so we cut a few more pieces of wood to make everything as rigid as it could be. In keeping with the spirit of the project, all the wood is salvaged from our remodel and so has different finishes on it… it's all going to be hidden inside under a coat of truckbed liner.

We also screwed in the new bracing to make it extra firm. We filled the screw holes like so:

We used a brand called Herculiner which was the only one available at our local Pep Boys equivalent. We used it on our last speaker project as well. It is designed for lining the backs of pickup trucks to keep them from scratching and so forth. A bit expensive- $30 a quart- actually the most expensive element in this setup since the other parts were already lying around the house, acting like the world owed them something. If you take a look below, you will see the first of several coats being applied over the inside of the box. We used a brush to paint it on:

After that, we cut some carpet foam to help absorb even more vibes. This was free since carpet stores always have extra pieces cluttering up their storage areas. We weren't entirely careful about getting the pieces to fit exactly since there is enough bracing inside to make that extremely difficult to do. Not critical. We then painted the bottom white, in case we decide to put some kind of light under it...

The rest of the area was filled with Acousta-stuf, which is a brand name speaker filler designed specifically to deaden vibration and clear up sound. Some say it's useless in subwoofers since it is designed more for higher frequencies, but we will experiment a bit to get the best results. It's the cottony looking stuff that you can barely see under the wire connections…

All there was to do at this point was assemble the parts and plug it in. Since we haven't put a "sub out" in our amp yet, we used the speaker level inputs on the amp plate so the volume control on the tube amp would control all the volume simultaneously. Otherwise, the sub volume would have to be controlled separately- annoying. We put little felt pads on the bottoms of the inset legs to make it easier to move around and to keep from scratching the floor.

How does it sound? Wicked. We needed punch, we got punch. The box dimensions sound just about right- no vibes or fuzziness. The power is just fine since there are those in the house who cannot stand any sound above a whisper- it will be a rare occasion when we actually get to pump it. Anyway, this was never expected to be very powerful, just to round out the sound- which it does… the bass is tight and invisible, the way it should be. For something that was designed to rattle your license plate, this fits right in with our predominately analog sound system.

And this is how it looks in our living room. We have a few too many records out at the moment, but this gives you some idea: